Fig. 3

(A) Use of the selected GAG-derived peptides and GAG protein for the identification of IFN-g producing CD8-specific T cells in fresh and frozen PBMCs of HIV-infected subjects. Fresh (upper panels) and frozen (lower panels) PBMCs of an HIV-1-infected subject were stimulated with recombinant GAG protein (left panels) or the pool of the selected GAG-derived peptides (right panels) as described in Materials and Methods. Each cytofluorimetric panel shows the CD8⁺ cells (on the ordinate) producing IFN-γ (on the abscissa). The frequency of IFN-γ/CD8+ cells over the total of CD3⁺ lymphocytes for each cytofluorimetric panel is reported. One of three independent experiments is shown. (B) Quantification of the CTL response against recombinant GAG protein (solid triangles) and the pool of selected GAG-derived peptides (open circles) in cell bank samples of Caucasian HIV-1-infected subjects at the time of their enrolment in the study and one month after interruption of HAART and in HIV-negative healthy controls. The number of CD8⁺ IFN-γ-producing cells/ml of blood is reported on the ordinate. Positive cut-off value of 50 IFN-γ Gag-specific CD8 cells/ml established on the mean + 3 SD of the negative control sample test results is reported as a dashed line.